This invention relates generally to a method for esterification of free fatty acids in triglycerides with alcohols to produce fatty acid alkyl esters.
High fuel prices and environmental concerns are driving development of alternative fuels, especially those derived from renewable resources. One such fuel, commonly known as “biodiesel” fuel, contains methyl esters of fatty acids, and is burned in diesel engines. Biodiesel fuel is produced from transesterification of triglycerides, such as vegetable oils with alcohols, typically with methanol. However, small amounts of free fatty acids present in triglycerides cause problems in the transesterification process, including foaming in the reaction mixture. The prior art discloses methods for esterification of these free fatty acids, e.g., in WO 2006/064643. However, the prior art teaches that resins with a high crosslinker level are needed to catalyze esterification of free fatty acids in triglycerides.
The problem addressed by this invention is to find an improved method for esterification of free fatty acids in triglycerides.